The bestselling bards of gonzo economics return with this new compendium of nifty, if occasionally shallow contrarian mind-warps. This time University of Chicago economist Levitt and journalist Dubner clothe their Freakonmics schtick in flimsy self-help garb by instructing readers on how to "think like a Freak": ignore conventional wisdom; focus on data; test theories with experiments; don't confuse correlation with causality (married people may be happier, they note, because no one wants to marry a grump); most of all, attend to the devious workings of callow self-interest that rule all things (a principle that comically backfires when one of them uses candy bribes to toilet-train his daughter). Levitt and Dubner apply these nostrums to problems having little to do with economics, including competitive hot dog-eating, why Nigerian con artists advertise themselves as Nigerian con artists, and the game-theoretical ploys of King Solomon and David Lee Roth. Their arguments are lucid, catchy, and sometimes dubious; their brief for the efficacy of medieval trial-by-ordeal is no more convincing than their hackneyed attack on Britain's national health system. The result is brief, blithe, but ill-digested provocations that stimulate controversy, but are too sketchy to settle it. (May)